This week, Canadian Pacific Railway Limited (USA) (NYSE: CP) announced its intention to file a request with the Surface Transportation Board (STB) asking for a declaratory order with respect to its proposed voting trust structure in its pursuit of a Norfolk Southern Corp. (NYSE: NSC) merger.

UBS analyst Thomas Wadewitz sees the filing as a clear indication that Canadian Pacific is still actively pursuing the merger, but believes that a negative STB response would likely mean the end of the road for the potential deal.

“A favorable response from STB would provide a leverage point for CP, while a negative response from STB would likely result in CP ending their campaign to combine with NSC (CP communicated in the past that voting trust approval is necessary to proceed with a potential deal),” Wadewitz explained.

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While the filing is good news for investors who see the merger as a positive, Wadewitz notes that a response from the STB could take up to four months.

Last week, Canadian Pacific announced it will be submitting a resolution to Norfolk Southern shareholders requesting discussions between the boards of the two companies concerning a potential merger. Shareholders would vote on the proposal at the annual meeting sometime between March 1 and June 30.

Disclosure: the author holds no position in the stocks mentioned.